Metal casting apparatus



Jan. 25, 1949. s. L.. PALMER ET AL 2,459,892

METAL CASTING APPARATUS Filed Dec. 14, 1945 5 Sheets-Sheet l III III'i'l Jan. 25, E949. s. L. PALMER ET Al. 2,459,392

METAL CAST ING APPARATUS 5 Sheets-Sheet 2 Filed Dec. 14, 1945 5%:Nw-:NTO s zdmfy L Palm BY Jagd 1% A8er/fes A RNEY Jan. 25, `1949. n s.L. PALMER ET AL 2,459,892

METAL CASTING APPARATUS Filed Dec. 14, 1945 5 Sheets-Sheet 3 INVENTORS514mg L Palmer BY lag/d Ber/fes 15 ATTRgm l Jam 25, 1949.

s. L. PALMER ET AL METAL CASTING APPARATUS `5 Sheets-Sheet 4 Filed Dec.14, 1945 VENTORS M 5ft/QS ftw ATTORNEY @muy Pm/ffm# BY Jagd 5sheetslsheet 5 Filed Dec. 14, 1945 ATTORNEY Patented Jan..l25, 1949UNITED STATES PATENT OFFICE METAL CASTING APPARATUS Application December14, 1945, serial No. 634,934

(ci. ca -7o) 3 Claims.

This invention relates to casting machines and more particularly tocasting apparatus of the closed split-mold type into which molten metalis introduced and cooled to produce cast shapes, the mold being openedand the casting ejected after solidiflcation.

Briefly, the invention provides improvements vin vcasting machines ofthe type comprising a vessel or receiver for holding a supply of moltenmetal to be cast and an initially closed mold which is in communicationwith the receiver and into which molten metal from the receiver lispumped. Operation of the casting machine `invention also makes itpossible, as a commercial operation, to standardize the shape, size andappearance of castings. Although the invention has been utilized forcasting white metal alloys, for example, in the production of ybarsolder, rods,

' etc., it is equally applicable for casting other metals and alloys,such as used to make weights, sinkers and the like.

In operating the machine of the invention, molten metal is introducedinto the mold and chilled to form the casting under controlledconditions, the temperature and pressure being regulated during castingto bring about filling of the mold and to provide for shrinkage feedingas the metal cools and solidifies. The sequence of operations lperformedduring the casting cycle is controlled by suitable electrical timingmechanism as hereinafter described.

The invention will be particularly described in connection with thecasting of solder bars but it will be understood that this is merelyillustrative of the invention and not limitative thereof. Other objectsand features of the invention will appear from the following detaileddescription of one embodiment thereof taken in connection with theaccompanying drawings, in which the same reference numerals indicatesimilar parts, wherein:

Fig. 1 is a vertical section view of the casting machine, illustratingdiagrammatically the melting furnace, molten. metal-receiver, molds andelectrical system for controlling the casting operations;

Fig. 5 is a detailed view in section of the splitmold, the mold beingshown in open position;

Fig. 6 is a plan View of the movable mold cover;

Fig. 37 is a similar plan 'View of the complementary mold half which isheld stationary during casting; v

Fig. 8 is a view in cross-section of the mold taken on the line 3 8 ofFig. `'l and looking in the direction of the arrows;

Fig. 9 is Van electrical diagram showing the layout of the generaltiming and control system.

Referring to the drawings, Figs. l and 2, the numeral I0 designates afurnace for melting pig metal I I from which castings are to beproduced, the metal being melted on a hearth I2, suitably heated by aburner I4 arranged therebeneath, as illustrated in Fig. 1. Molten metalin the melting furnace ows from the hearth I2 into a receiver or vessell5 through a charging spout or ladle I6.

A float il positioned in the melt I8 operates through'conventionalmechanism, not shown, to control the fuel supply to burner I4, whereby arelatively constant amount of molten metal is maintained in the receiverI5 during casting.

Thermostatic control of the burner I9 is provided by the thermostat 20which operates through associated mechanism 2| to vary the setting ofthe burner which in turn maintains the melt I8 at the desired operatingtemperature. Where it is desired to limit the degree of oxidation of themetal during melting, the atmosphere in the furnace is suitablycontrolled.

Molten metal is pumped from the receiver I5 to the casting mold,generally designated by reference character 22, through a manifold pipeline 2l by a submerged centrifugal pump 25, the pump being suitablysupported while submerged in the melt and connected to the manifold, asillustrated in Fig. l. Excess molten metal entering the manifold isreturned to the receiver through pipe 26, being discharged beneath thesurface of the melt as shown at 2l. By this arrangement, a closed moltenmetal circulating system is provided whereby oxidation of the metalduring casting is held to a minimum.

To operate the centrifugal pump 25, a variable speed motor 55 issuitably mounted over the melt on a supporting frame structure 3| and isdrivingly connected to the vertically disposed pump propeller shaft 52,as illustrated in Fig. 1. For controlling the pressure oi.' the moltenmetal supplied to the mold from the manifold, a throttle valve 55 isplacedin line 25. This throttle valve is operated by a piston actuatedrod 55 working in a hydraulic cylinder Il. Fluid under pressure foractuating the piston in cylinder 51 flows through pipe lines 35 and 55which are, in turn, connected to a pressure control valve 55, thecontrol valve being operated electrically in accordance with the settingof the general timing and relay system shown schematicallyvin Fig. 4.The pressure of the molten metal flowing to the mold may also be variedby changing the speed of motor 35 using similar electrical timingmechanism. These two methods of pressure control may be used singly orin unison, as desired.

. The general arrangement of the mold and associated operating mechanismis illustrated in Fig. 3. The mold 22, which is suitably supportedvertically, comprises a base or mold proper section 55 and a.complementary cover section 5| supported for movement into closed andopen position. In the preferred form, illustrated in Fig. 3, the moldcover is hinged to the base l mold half 55 at its upper end, the moldbase portion being rigidly supported while the cover is pivotallysecured thereto as at 52. A

In theembodiment illustrated, water under appropriate pressure isutilized to actuate the moving parts of the casting apparatus and coolthe mold, being supplied through pipe line 55 from a suitable source anddischarged through line 55 after use. Cooling water is conducted fromthe su l line 55 to the mold halves 55 and 5I by pp y o the mold duringsolidiilcation of the casting fill.-

conduits 55 and 55 respectively, and from' the mold to the dischargeline 55 by conduits 51 and 55, as illustrated in Figs. 2 and 3. Ailexible hose connection is used for water lines 55 and 55 to permitmovement of the mold cover 5| during operation of the casting machine.Where it is 45 desired,I other and independent fluid pressure means,such as air, steam or oil,l may be used to actuate the moving parts ofthe casting apparatus, cooling water for the mold being supplied througha separate line.

For opening and closing vthe mold, a hy.- draulically operated cylinder55 is utilized, as illustrated in Fig. 3. A piston rod 52 working in thecylinder 55 is pivotally connected at its outer end, by a pin 55, to thepair of angle sections 55 which are bolted to the mold cover 5| as shownin Figs.

-3, 5 and 6. Hydraulic fluid for actuating the piston is conducted fromthe control valve 55 to the cylinder by conduits 55 and 51. A similarlypiston operated rod 15, working in the hydraulic cylinder 12, isprovided to actuate the ejector pin 15r and eject the casting 15 uponopening the mold. Fluid pressure for operating the ejector-pin-actuatlng cylinder 12 is conducted through the pipes 11 and 15 whichare connected to the control valve 15. Suitable handling, marking andpackaging mechanism for the casting may be provided, such as illustrateddiagrammatically at 55, 5| 'and 52 respectively, in Fig. 3.

'I'he -detail construction of the molds is illus-V trated in Figs. 5, 6,I and 8. The mold half 55 and hinged cover section 5| are each providedwith a water cooled back portion which is designed to providediilerential cooling between the upper and lower ends 'of the mold. Thelowest tem- 4 perature is maintained at the top of the mold byintroducing the cooling water at the upper end, as indicated at 55 and55, and withdrawing it at the bottom, as shown at 55 and 55. Ther- 5mostats 55 and 5 5 are placed in the outlets- 55 and 55, respectively,which operate to increase or decrease the amount of cooling wateradmitted in accordance with the temperature variation of the waterleaving the mold'. For example, when the temperature of the dischargewater exceeds length, suitable bailles 55 are cast in the water cavityto direct4 the water flow in a zig-zag path downwardly through thecooling chamber, as indicated by the arrows in Figs. 6 and '1.

Molten metal during casting, is admitted at the bottom of the mold underlow pressure to avoid splashing and squirting-the mold being filled asthe pressure in line is increased by closure of' valve 55. Air vents 52are provided near the top of each mold cavity as illustrated in Figs. 6

25 and '1, to assist in rapidly evacuating the mold of air when it isbeing illled. Where it is desired, a neutral or reducing atmosphere maybe employed in themold, as for example, when casting oxygen-free metal.As the molten metal rises in the mold, it cools due to contact with themold,

the coldest metal Ibeing always at the top of the mold. By utilizing themold construction and arrangement illustrated, the temperature gradientduring cooling of the cast metal is such that the directionalsolidication of the casting is opposite to the iiow of the metalentering the mold.

As the mold nils and solidlilcation progresses molten metal at the lowerend of the mold, being under maximum pressure, continues toA flow intoing shrinkage voids produced as the freezing progresses downwardly tothe end of the mold. This results in the production oi.' a casting whichAis free from shrinkage voids. After the metal in the mold hascompletely solidiiled and there is no further flow of the metal to themold cavity, freezing progresses slightly into the entry port or gate55. A similar port is provided at the lower end of each mold cavity 55,as shown in Fig. 7. The

mold illustrated comprises only two pockets or mold cavities 55, withassociated ejector pin means 15, but it will be appreciated that this ismerely exemplary and that molds may be used, in practicing theinvention, having any desired number of cavities depending upon the typeof castings being made, sizes, and capacities required.

Operation of the various casting elements is electrically controlled,the general layout oi' the system being shown in Figs. 4 .and 9. Fourtime u' switches |5l, |52. |53 and |55 and six relays |55,

V7'0 scribed as follows:

Assume that the mold is 'closed with ejector pins 15 in retractedposition flush with, and thus constituting a part of, the mold inner'wall, molten metal is ilowing under low pressure 7s through mammie u,and unie switches m,

' solenoid valve metal enters ,tire-:mold: cavities '90' through portsilffrom the coupling member-Qnadapten .91, being deflectedthereigntobybaille, 98- as- .illustrated in F185. 5. and Asthe mold fills,pressure in the manifold 24 is. increased by. partial or. substantialclosing of. ,they-alve 35., through .actuation of, the 40, toprovldesulcient pressure .for ,iillins.,sollidifisation..shrinkagevoids. Directionali-solidieation is -effected, by the 4cooling watercirculated .freezing ofI thebar. at the ports 95.-,-

When the metal-in vthe, mold hasbeen completly ,solidified-the moldcover M iswithdrawn after the pressure .in-the manifold line 24 lhasthe. receiver-l through the line 24 and adapter.

:91 itis deflected upwardly and againstthe ports 95 by thebaiiles V9.0,which are positionedin the adapter opposite the ports, as shown in Figs.5 and' 7u By. this construction and use of the apparatus the. solidifiedsprue portion remaining in the ports y95, after the casting has beenejected, is quickly remeit'edfwhereby, upon the withdrawal .of .theejector pins 15, molten metal is permitted to again flow through theports 95 into the mold.

Upon closure of the mold, the hydraulic cylinder 1 12 is actuatedtdcauseretraction Aof the ejector pins.l Thereafter the pressure ofmolten metal qwing in manifold 24 is increased, by operation of..Ivalvel 35, causing filling of the mold, thus starting a new cycle.

' Utilizing conventional electrical time switches and relays` connectedas indicated by the diagrams, Figs. 4 and 9, theA proper sequence ofoper- .ation of .the machine elements is provided. Utilizing theinvention, solder.- bars weighing 11,52 pounds have been cast on a timecycle of l5 to.23 seconds. ;The cast bars were of uniform size andvshape-'and lthe maximum weight variation was le 'ounce` perbar. Inthisconnection, it will be-appreciated that the time cycle may be variedto suit different metals and casting conditions.

The general timing control system, for operating the machine elements inproper sequence is illustrated in Figs. 4 and 9. Using a power line of115 volts and 60 cycle, as indicated in the Wiring diagram of Fig. 9, acasting cycle is initiated by depressing the momentary-contact pushbutton marked Reset, Fig. 9.

Current flowing through undervoltage coil A of relay |05 seals itself inthrough its normally open interlock B. Relay |06 being de-energized, acircuit is prepared through normally closed pole C for energizing thepressure control timer |0|. The pointer of the timer is at zero readingand, accordingly contacts E are closed so that the clutch coil F isenergized and the pressure control timer starts timing. Clutch contactsG immediately close, maintaining current to the clutch coil F, after'thepointer of the pressure control timer leaves the zero station.

When the pre-set pressure control timer comes to the end of its timeperiod contacts H are closed passing current through the relay coil Ipicking up the relay |01 whose normally closed pole vJ through the backof the mold' vhalves,4 as previouslyv described, tocause final opensde-energizlng coil K of relay |09. This ends the time period' controlledby the pressure control timer |0|. At the start of this timer, thenormallyl 4open contacts Y of relay |09 were closed energizing thesolenoid valve coil 40 in the circuit .PCV thereby closing the throttlevalve whereby molten metal under high pressure is established in line 24causing mold 22 to be completely lled. At the end of the pressurecontrol timing period, the solenoid coil operating the throttle valve 35is de-energized, opening this valve and establishing low pressure inline 24.

n At the end of the pressure control timing period, relay |01 isenergized and one of its normally open poles L energizes the clutch coilM of the mold timer |02. This mold timer immediately starts timing andcontinues to time as long as contactsl Hvremain closed. Contacts H' aremaintained closed during the period the clutch coil F is kept energized.When the mold timer |02 starts to time, the solenoid coil of the mold-valve 65 is energized, through line connection MV, to hold the moldopen. After the pointer of the mold timer |02 has moved through apre-set time interval its contacts N close energizing mold relay coil Ooperating relay |08 whose normally closed pole P opens de-energizing thecircuit to the mold solenoid valve 65 permitting the mold to close.'I'he mold is held open for a pre-set time interval which starts to runat the termination of the pre-set time interval established by the ipressure control timer |0|.

lWhen the time interval controlled bythe pressure control timerterminates, another open pole contact Q` of relay .|01 closes energizingclutch coil R of ejector pin delay timer |03. This starts the ejectorpln delay timer on its timing interval,

' the timer starting to run only when the pressure |03, its contacts Sclose energizing the clutch coil vcontrol timer |0| has terminated itstiming interval. By adjusting the ejector pin delay timer.'

the time interval of delay between the instant the solenoid valve coil65 is energized and actuation of the ejector pin solenoid valve 19 isreadily controlled and pre-set.

Upon timing out of the ejector pin delay timer T of the ejector pintimer |04, and starting this timer timing. When the timer |04 starts totime, it energizes the ejector pin solenoid valve coll 19 in line EPV,through contact U which operates to move the pin to out position.De-energizing of this coil causes the ejector pin to be moved to in orretracted position. The ejector pin timer |04 controls the time intervalduring which the ejector pin is out, the interval being pre-set byadjustment of the timer |04.

At the end of the time interval controlled by this ejector pin timer,its contacts V close, energizing coil W of relay |06 whose normallyclosed pole X opens to de-energize the coil Z of relay ||0 whereby thecircuit to ejector pin solenoid valve 19 is broken. Through the secondnormally closed pole of the ejector pin relay |06, the clutch coil ofpressure control timer |0| is de-energized. The time-closing contacts Hof the pressure control timer |0| open, after suicient time elapses topermit the pointer to move far enough toward zero position to allowthese contacts to separate.

After this occurs, relay |01 is de-energized, and its two normally opencontacts return to open position. This action de-energizes the clutchcoils of the mold timer |02 and the ejector pin delay timer |03. Uponde-energizng of the ejector pin delay timer clutch coil and the pointerhas returned toward zero position suillciently to contacts oi this relayare now closed automaticallystarting a newlcycle. Limit switches LSI,L82, LSI and LSI in the timers lli, III, III und I, respectively, arenormally closed, being adapted to open when the pointer of the timingmotor reaches full scale position, thereby protectlng the time switchesfrom over travel with possible attendant damage to the instruments.

Utilizing the present invention to cast solder bars, no mold dressing isrequired, however, it will be appreciated'that when the use of molddressing is necessary, suitable means may ,be provided for doing-this,tor example, byarranging to spray the mold with bone-ash slurry. or thelike.

at intervals to prevent sticking.

While the invention is particularly adapted to the casting of whitemetals and lead alloys, it will be understood that the principlesthereof are applicable generally to the casting of other metals andalloys which present problems similar to those encountered in castingwhite metal. Further it will be appreciated that various omissions,substitutions and changes may be made by those skilled in the artwithout departing from the spirit of the invention.

What is claimed is:

1. In a machine for casting metals and alloys having a vessel forholding molten metal to be cast, a split-type mold having a port foradmitting molten metal thereinto, and a Lconduit for molten metalinterconnecting said vessel and mold via.` said port, the combinationwith. said I. mold of a reciprocable pin which in retracted position isclear of the port and mold cavity and in extended position enters thecavity a sumicent distance to constitute'both a closure for the port andan ejector of the casting from the mold.

2.In a casting machine of the class described having a vessel forholding molten metal to be cast, a vertically-disposed mold oi' thesplit-type hinged at the top and with a port near the bottom for ingressof molten metal to the mold cavity, a pump in said vessel, a conduitinterconnecting bination with said mold of a reciprocable mem- 4 berconstitutinga 8 said pump and port and returning to said vessel with a.valve in the return portion o! said conduit, and passageways in saidmold so positioned as to eiiect progressive solidiiication of the cast'-ing from the top downwardly to the port when cooling fluid is circulatedtherethrough, the com- Dlrtf the mold Vinner will when in retractedposition, and a combined port closure and castingl ejector when inextended position.

3. In' metal casting apparatus having a vessel for holding molten metalto be cast, a split-type mold, a pump, a conduit for molten metal havingone end connected Ato said pump and. the other end open, both ends beingpositioned below the metal line oi' the vessel, said conduit comprisinga molten metal supplyfsection and a molten metal return section bothextending exteriorly of said vessel, and acoupling member providing apassageway for molten metal between slid supply section and the moldcavity. the combination therewith of a throttle valve in said moltenmetal return section having a valve operating mechanism and timingdevice associated therewith controlling the closing and opening of saidthrottle valve in accordance with a predetermined set-- ting of thetiming device.

SIDNEY L. PALMER. LLQYD M. BDCKES.

REFERENCES CITED The following references are of recordy in the tile ofthis patent:

UNITED s'iwncs PA'rsN'ra Number

